Schumaker, 36, was in camp on a Minor League deal. The Padres had every intention of looking at him for a bench job -- a left-handed hitter off the bench, someone with versatility and a player with a strong clubhouse presence.
But Schumaker told Green privately that he had reached the end of the road as a player.
"He's at a point in his journey where it's time to move on," Green said. "We spent an hour together, going through his career and what brought him to his decision. He's spent himself in this game as a player. His body hurts when he gets up in the morning. He's grinded it as hard as it can.
"He thinks it's time for that job to go to someone else and not himself."
"His career was lived with class and dignity. He led by example and I have nothing but respect for him." -Andy Green pic.twitter.com/mRP86LyF0U
Schumaker, who earned World Series rings with the Cardinals in 2006 and '11, was 0-for-8 in three Cactus League games this spring. He started games at second base and in right field.
Schumaker, who wasn't available for comment Wednesday, finished his career with a .278/.337/.364 line in 1,149 games.
Schumaker recently told MLB.com that this stop in San Diego would be the last in a career that began in 2001, when he was drafted by the Cardinals in the fifth round.
"I didn't think I would have one day in the big leagues. I know it's a short window, being a player," Schumaker said last week. "I love the game. I know it won't be there forever."
Green said Schumaker addressed the team before Wednesday's workout.
Green also said the conversation he had with Schumaker was eerily similar to the one he had with now-Mets manager Terry Collins at the end of the 2010 season. Collins was the Mets' Minor League field coordinator at the time and Green, who was then 32, was ready to end his playing career.
Collins tried to talk Green out of stepping away from the game. Green didn't try the same with Schumaker.
"[Schumaker] didn't take the decision lightly," Green said. "He said some of the same things I said to Terry Collins [six] years ago: 'I might be able to trick some people in the game, but I can't trick myself. I can't catch up to a 95 mph fastball anymore. I can't move like some of these guys can move. My body hurts like crazy getting ready.'"
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.